There is conventionally known a technology that performs overlapping display of a highlight image to a notification object ahead of a vehicle using a virtual image display apparatus such as a head-up display so that the highlight image represents the presence of the notification object.
There is known a frame-shaped highlight image surrounding a notification object or a linear highlight image displayed below a notification object.
A positional difference occurs between a notification object and a highlight display based on the detection accuracy of a radar to detect the notification object or an error resulting from installing or manufacturing a head-up display or a windshield. The positional difference may not only annoy a user, but also allow the user to incorrectly recognize the notification object in some cases.
To solve this, there is proposed a technology that predetermines a sufficiently large area represented by a highlight image so that a notification object reliably fits into an area indicated by a frame-shaped highlight image (see patent literature 1).